1. Field of the Invention
This invention relates generally to glue applicators and more particularly to a glue applicator for rolling a thin film of glue onto a work sheet, such as one folded flap of a flattened carton structure which is then fed into a carton sealing machine between feed rolls of the machine which compress the flattened carton structure to bond the glue coated flap to a second overlying flap.
2. Discussion of the Prior Art
As will appear from the ensuing description, the glue applicator of this invention may be used for various purposes. The applicator, however, is primarily intended for use on a particular type of carton sealing machine and will be described in this context.
The particular sealing machine referred to is a carton taping machine manufactured by the General Corrugated Machinery Co., Inc., of Palisades Park, N.J. Since this machine is conventional and need not be fully explained to understand the invention, only a brief description of the machine will be presented. The machine is adapted to receive flattened carton structures each having a generally rectangular panel with a fold line between and parallel to two opposite edges of the panel, and flaps hinged to the panel along these and the other panel edges. In the flattened condition of the carton structure the two flaps along the two mentioned parallel panel edges are folded inwardly against the same side of the panel with the outer edge portion of one flap, referred to as the outer flap, overlying the other edge portion of the other flap, referred to as the inner flap. The remaining flaps of the carton structure are unfolded and lie in the plane of the panel.
This flattened carton structure is fed edgewise into the machine between feed rolls which compress the structure to press its overlapping inner and outer flaps firmly together. As this compressed carton structure proceeds through the machine adhesive tapes or strips are applied to its overlapping flaps to firmly join the flaps after which the carton structure is erected to carton shape or otherwise handled.
A variety of glue applicators have been tried on carton sealing machines of the kind described. However, these existing applicators are not totally satisfactory, at least for the particular carton sealing machine described, for various reasons, foremost among which are that they apply a bead of glue which must be spread by the pressure exerted on the carton flaps to be glued and hence use excessive glue which not only is uneconomical but also frequently results in contamination of the sealing machine pressure rolls and other parts and requires a long drying time for the bonded surfaces. This long drying time, of course, reduces the carton through put rate of the carton machine.